Abstract: A propeller device has a propeller hub which is elongated along the rotational axis and a propeller blade which radially extends from the propeller hub. The propeller hub and propeller blade are configured so that when the propeller device is forwardly rotated, a first portion of the propeller hub on a first side of the propeller blade encounters a positive pressure and a second portion of the propeller hub on an opposite, second side of the blade encounters a relatively lower pressure or suction, and further so that when the propeller device is reversely rotated, the second portion of the propeller hub encounters a positive pressure and the first portion of the propeller hub encounters a relatively lower pressure or suction. An exhaust vent hole is located in the first portion of the propeller hub and configured to vent exhaust gases from the marine drive via the propeller hub as the propeller device is reversely rotated, thereby enhancing reverse thrust performance of the propeller device.

Abstract: A marine propulsion device includes an internal combustion engine driving a driveshaft into rotation and a starter-generator motor in a torque transmitting relationship with the driveshaft. The starter-generator motor is alternately operable in a positive torque mode where it is powered by a battery to exert a positive torque on the driveshaft, and in a negative torque mode where it exerts a negative torque on the driveshaft and generates a charge to the battery. A control module is configured to receive an engine RPM, determine an engine RPM drop rate, and determine that the engine RPM drop rate exceeds a threshold drop rate. The starter-generator motor is then operated in a positive torque mode based on the engine RPM drop rate when the engine RPM drop rate exceeds the threshold drop rate.

Abstract: A method of controlling two or more propulsion devices on a marine vessel includes receiving a vessel speed, determining that the vessel speed is below a first vessel speed threshold, receiving an operator thrust demand, and determining that the operator thrust demand is below a first demand threshold. At least one of the two or more propulsion devices is then turned off, and a thrust output of at least one remaining propulsion device is adjusted based on the operator thrust demand.

Abstract: An outboard motor includes an internal combustion engine powering the outboard motor and a cowl covering the engine and having a vent allowing air under the cowl. A throttle body meters flow of the air into the engine and an intake structure downstream of the throttle body delivers the metered airflow to one or more combustion chambers in a cylinder block of the engine. A sound enhancement assembly in acoustic communication with the intake structure collects sounds emitted by the engine. The sound enhancement assembly is configured to amplify a subset of the collected sounds that have frequencies within a desired frequency range. A method for modifying sounds produced by an air intake system of an internal combustion engine powering an outboard motor is also disclosed. The method includes positioning a sound enhancement assembly in acoustic communication with an air intake passageway located downstream of the engine's throttle body.